how much energy must be transferred to a normal incandescent bulb (efficiency 0.05) for it to transfer 9J of energy by light?

Revise energy transfers and use sankey diagrams to calculate the efficiency of these conversions with BBC ... Efficiency is a measure of how much useful energy is converted. Part of ... This is the Sankey diagram for a typical filament lamp: 100 joules of electrical energy is converted to 10 joules of light energy and 90 joules.

Explanation:

force required to detach it is given by

charges are taken to be fundamental charge

now we have

so above is the minimum distance at which it will detach

+15-35=-20

going in opposite directions